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DeReference the codebase

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This change replaces all Ref objects in the code with Key objects. These are
stored in datastore as the same object (raw datastore keys), so this is not
a model change.

Our best practices doc says to use Keys not Refs because:
 * The .get() method obscures what's actually going on
   - Much harder to visually audit the code for datastore loads
   - Hard to distinguish Ref<T> get()'s from Optional get()'s and Supplier get()'s
 * Implicit ofy().load() offers much less control
   - Antipattern for ultimate goal of making Ofy injectable
   - Can't control cache use or batch loading without making ofy() explicit anyway
 * Serialization behavior is surprising and could be quite dangerous/incorrect
   - Can lead to serialization errors. If it actually worked "as intended",
     it would lead to a Ref<> on a serialized object being replaced upon
     deserialization with a stale copy of the old value, which could potentially
     break all kinds of transactional expectations
 * Having both Ref<T> and Key<T> introduces extra boilerplate everywhere
   - E.g. helper methods all need to have Ref and Key overloads, or you need to
     call .key() to get the Key<T> for every Ref<T> you want to pass in
   - Creating a Ref<T> is more cumbersome, since it doesn't have all the create()
     overloads that Key<T> has, only create(Key<T>) and create(Entity) - no way to
     create directly from kind+ID/name, raw Key, websafe key string, etc.

(Note that Refs are treated specially by Objectify's @Load method and Keys are not;
we don't use that feature, but it is the one advantage Refs have over Keys.)

The direct impetus for this change is that I am trying to audit our use of memcache,
and the implicit .get() calls to datastore were making that very hard.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=131965491
This commit is contained in:
cgoldfeder 2016-09-01 10:44:23 -07:00 • committed by Ben McIlwain
parent 1a60073b24
commit 5098b03af4
119 changed files with 772 additions and 817 deletions
Download patch file Download diff file Expand all files Collapse all files

39
java/google/registry/model/EppResourceUtils.java
View file

@ -17,7 +17,7 @@ package google.registry.model;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.collect.Iterables.transform;
import static google.registry.model.RoidSuffixes.getRoidSuffixForTld;
import static google.registry.model.index.ForeignKeyIndex.loadAndGetReference;
import static google.registry.model.index.ForeignKeyIndex.loadAndGetKey;
import static google.registry.model.ofy.ObjectifyService.ofy;
import static google.registry.util.DateTimeUtils.isAtOrAfter;
import static google.registry.util.DateTimeUtils.isBeforeOrAt;
@ -25,7 +25,6 @@ import static google.registry.util.DateTimeUtils.latestOf;
import com.google.common.base.Function;
import com.googlecode.objectify.Key;
import com.googlecode.objectify.Ref;
import com.googlecode.objectify.Result;
import com.googlecode.objectify.util.ResultNow;
import google.registry.config.RegistryEnvironment;
@ -98,20 +97,20 @@ public final class EppResourceUtils {
*/
public static <T extends EppResource> T loadByUniqueId(
Class<T> clazz, String foreignKey, DateTime now) {
// For regular foreign-keyed resources, get the ref by loading the FKI; for domain applications,
// we can construct the ref directly, since the provided foreignKey is just the repoId.
Ref<T> resourceRef = ForeignKeyedEppResource.class.isAssignableFrom(clazz)
? loadAndGetReference(clazz, foreignKey, now)
: Ref.create(Key.create(null, clazz, foreignKey));
if (resourceRef == null) {
// For regular foreign-keyed resources, get the key by loading the FKI; for domain applications,
// we can construct the key directly, since the provided foreignKey is just the repoId.
Key<T> resourceKey = ForeignKeyedEppResource.class.isAssignableFrom(clazz)
? loadAndGetKey(clazz, foreignKey, now)
: Key.create(null, clazz, foreignKey);
if (resourceKey == null) {
return null;
}
T resource = resourceRef.get();
T resource = ofy().load().key(resourceKey).now();
if (resource == null
// You'd think this couldn't happen, but it can. For polymorphic entities, a Ref or Key is
// of necessity a reference to the base type (since datastore doesn't have polymorphism and
// You'd think this couldn't happen, but it can. For polymorphic entities, a Key is of
// necessity a reference to the base type (since datastore doesn't have polymorphism and
// Objectify is faking it). In the non-foreign-key code path above where we directly create
// a Ref, there is no way to know whether the Ref points to an instance of the desired
// a Key, there is no way to know whether the Key points to an instance of the desired
// subclass without loading it. Due to type erasure, it gets stuffed into "resource" without
// causing a ClassCastException even if it's the wrong type until you actually try to use it
// as the wrong type, at which point it blows up somewhere else in the code. Concretely,
@ -286,13 +285,13 @@ public final class EppResourceUtils {
private static <T extends EppResource> Result<T> loadMostRecentRevisionAtTime(
final T resource, final DateTime timestamp) {
final Key<T> resourceKey = Key.create(resource);
final Ref<CommitLogManifest> revision = findMostRecentRevisionAtTime(resource, timestamp);
final Key<CommitLogManifest> revision = findMostRecentRevisionAtTime(resource, timestamp);
if (revision == null) {
logger.severefmt("No revision found for %s, falling back to resource.", resourceKey);
return new ResultNow<>(resource);
}
final Result<CommitLogMutation> mutationResult =
ofy().load().key(CommitLogMutation.createKey(revision.getKey(), resourceKey));
ofy().load().key(CommitLogMutation.createKey(revision, resourceKey));
return new Result<T>() {
@Override
public T now() {
@ -310,10 +309,10 @@ public final class EppResourceUtils {
}
@Nullable
private static <T extends EppResource> Ref<CommitLogManifest>
private static <T extends EppResource> Key<CommitLogManifest>
findMostRecentRevisionAtTime(final T resource, final DateTime timestamp) {
final Key<T> resourceKey = Key.create(resource);
Entry<?, Ref<CommitLogManifest>> revision = resource.getRevisions().floorEntry(timestamp);
Entry<?, Key<CommitLogManifest>> revision = resource.getRevisions().floorEntry(timestamp);
if (revision != null) {
logger.infofmt("Found revision history at %s for %s: %s", timestamp, resourceKey, revision);
return revision.getValue();
@ -336,19 +335,19 @@ public final class EppResourceUtils {
* <p>This is an eventually consistent query.
*
* @param clazz the referent type (contact or host)
* @param ref the referent key
* @param key the referent key
* @param now the logical time of the check
* @param limit max number of keys to return
*/
public static List<Key<DomainBase>> queryDomainsUsingResource(
Class<? extends EppResource> clazz, Ref<? extends EppResource> ref, DateTime now, int limit) {
Class<? extends EppResource> clazz, Key<? extends EppResource> key, DateTime now, int limit) {
checkArgument(ContactResource.class.equals(clazz) || HostResource.class.equals(clazz));
return ofy().load().type(DomainBase.class)
.filter(
clazz.equals(ContactResource.class)
? "allContacts.contactId.linked"
: "nameservers.linked",
ref)
key)
.filter("deletionTime >", now)
.limit(limit)
.keys()
@ -358,7 +357,7 @@ public final class EppResourceUtils {
/** Clone a contact or host with an eventually-consistent notion of LINKED. */
public static EppResource cloneResourceWithLinkedStatus(EppResource resource, DateTime now) {
Builder<?, ?> builder = resource.asBuilder();
if (queryDomainsUsingResource(resource.getClass(), Ref.create(resource), now, 1).isEmpty()) {
if (queryDomainsUsingResource(resource.getClass(), Key.create(resource), now, 1).isEmpty()) {
builder.removeStatusValue(StatusValue.LINKED);
} else {
builder.addStatusValue(StatusValue.LINKED);